Conventional automatic conveyors for an original document in a duplex photocopy machine or the like are disclosed in Japanese patent applications (OPI) Nos. 23039/86 and 23040/86 (the term "OPI" as used herein means an "unexamined published application"). Each of the conventional automatic conveyors basically comprises an original sender for sending out, one by one, both-side originals put in an original housing section and a common, i.e., for one-side and both-side originals, conveyance means for conveying the original document sent out by the original sender toward an original document copying position on a platen. A both-side conveyance means removes the original document from the platen, inverts the original after one side has been copied, and conveys the original back to the original document copying position on the platen. A discharging conveyance means discharges the original document on the platen after the other side of the original has been copied.
In the conventional automatic conveyors described in the above applications, the front edge of the original document is aligned immediately before the original is moved into an original introducing section for the platen. The original is thereafter moved to the original copying position on the platen so that the image of the original is properly copied onto copying paper. However, since the width of each of the conveyance passages of the common conveyance means and the both-side conveyance means is provided with some allowance for the prevention of paper jamming or the like, the original is likely to be skewed while being conveyed by each of the conveyance means. Consequently, the side edge of the original is likely to be misaligned in the original copying position on the platen. Therefore, there is a problem that the position of the image of the original reproduced on the copying paper is likely to be somewhat misaligned.
Although the length of the conveyance passage of the common conveyance means from the original housing section to the platen does not need to be large, the length of the conveyance passage of the both-side conveyance means has been considerably greater because it is necessary to both remove the original from the platen and to invert the original by the both-side conveyance means. For that reason, the original is likely to be more skewed in the conveyance passage of the both-side conveyance means causing the position of the original to be misaligned on the copy.
Thus, in a conventional automatic duplex photocopy machine, a paper inverting mechanism or the like is provided at the paper conveyance passage of the copying machine so that after copying is performed on one side of the copy paper, the paper is inverted and conveyed to an image transfer section and an image is transferred to the other side of the paper. To this end, the conventional duplex photocopy machine is integrally provided with an automatic original conveyor so that the image of one side of an original placed on a platen by the automatic original conveyor is scanned, and the original is thereafter inverted and again placed on the platen by the automatic original conveyor so that the image of the other side of the original may be scanned and transferred to the other side of the paper.
In the automatic original conveyor disclosed in OPI No. 23040/86, an original conveyance belt unit 126 is provided over a platen 125, as shown in FIG. 14. The automatic original conveyor 101a functions so that an original 103 is sent out from the original housing tray 102 of the conveyor by an original sender 105 and conveyed to the platen 125 through a conveyance passage shown by arrows in FIG. 14. After the original is conveyed to the platen 125 by the original conveyance belt unit 126 and the image of one side of the original is scanned, the belt unit is driven in the reverse direction to convey the original to an inverting section 130 where it is inverted and then conveyed back to the platen through complicated passages to scan the image of the other side of the original. The original is then discharged to a discharge tray.
Another conventional automatic original conveyor is disclosed in Japanese patent application (OPI) No 8834/85. In the automatic original conveyor, a nearly U-shaped inverting passage is provided in the face of the end of a platen so that the original, the image of one side of which has already been scanned, is moved through the inverting passage as the original is discharged by an original conveyance belt unit. The original is moved through the inverting passage and is conveyed again to the platen by the original conveyance belt unit. The original is positioned on the platen so that the image of the other side of the original can be scanned to transfer the image to the reverse side of the paper, on the observe side of which the image of the former side of the original is already copied, to complete both-side copying.
In the above-described conventional automatic original conveyors, an exclusive inverting passage is provided separately from the common, i.e., original conveyance passage. For that reason, a passage for sending out the original from the original housing tray and the inverting passage are separately provided so that operational members are operated separately from each other. Therefore, the original conveyance passage and the inverting passage need to be provided with separate drive mechanisms, aligning units, control units and so forth. As a result, the structure of the automatic original conveyor is complicated and large in size. Since the inverting passage is relatively long, jamming is more likely to occur in the inverting passage, and the original conveyance passage and the control or the like of the operational members is complicated.